WASHINGTON -LRB- CNN -RRB- -- Republican presidential front-runner Sen. John McCain on Thursday defended his statement that U.S. troops could spend `` maybe 100 '' years in Iraq -- saying he was referring to a military presence similar to what the nation already has in places like Japan , Germany and South Korea .

Sen. John McCain defends his stance on troops in Iraq Thursday on CNN 's `` Larry King Live . ''

This week , Democratic presidential candidates Sen. Hillary Clinton and Sen. Barack Obama both took McCain to task for the comments , saying that if he 's elected he would continue what they call President Bush 's failed policies in Iraq .

`` It 's not a matter of how long we 're in Iraq , it 's if we succeed or not , '' McCain said to CNN 's Larry King .

`` And both Sen. Obama and Clinton want to set a date for withdrawal -- that means chaos , that means genocide , that means undoing all the success we 've achieved and al Qaeda tells the world they defeated the United States of America .

`` I wo n't let that happen . ''

Last month , at a town hall meeting in New Hampshire , a crowd member asked McCain about a Bush statement that troops could stay in Iraq for 50 years .

`` Maybe 100 , '' McCain replied . `` As long as Americans are not being injured or harmed or wounded or killed , it 's fine with me and I hope it would be fine with you if we maintain a presence in a very volatile part of the world where al Qaeda is training , recruiting , equipping and motivating people every single day . ''

The remaining Democratic contenders for the White House seized on the statement . Watch McCain talk about Mitt Romney 's endorsement and his critics on the right ''

`` He said recently he could see having troops in Iraq for 100 years , '' Clinton said at an Arlington , Virginia , rally last week in a line she 's repeated on the campaign trail . `` Well , I want them home within 60 days of my becoming president of the United States . ''

Obama took a similar tack .

`` Sen. McCain said the other day that we might be mired for 100 years in Iraq -- which is reason enough not to give him four years in the White House , '' Obama has said on several occasions .

McCain told King he thinks opponents are taking the quote out of context . He said any long-term troop presence in Iraq would depend on agreement from the Iraqi government .

`` If they do n't want to and we do n't feel a need to do so , obviously , the whole thing is keyed to Americans being able to withdraw and come home with honor , not in defeat , '' he said .

McCain was endorsed Thursday by former Massachusetts Gov. Mitt Romney , once considered his fiercest rival for the GOP nomination .

Former Arkansas Gov. Mike Huckabee remains in the race , although McCain has an overwhelming advantage in the number of delegates earned for this year 's Republican convention . E-mail to a friend

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McCain : referred to a military presence like U.S. has in Japan , Germany , South Korea

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`` It 's not a matter of how long we 're in Iraq , it 's if we succeed or not , '' McCain said

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Sen. Hillary Clinton : `` I want them home within 60 days of my becoming president ''